To enhance the population of fish such as trout and salmon which spawn in the gravel of running streams and rivers, or in lakes where wave action causes water movement, incubating devices have been provided in which eggs may be placed and located in the gravel to afford a degree of protection to the eggs and the hatched fry from predators. An example of such a device is shown in U.S. Pat. No. 2,611,337, which also describes other prior devices. These prior devices are characterized in comprising a perforated box with a single compartment in which fertilized, eyed eggs are placed, the box then being positioned in the gravel. The emerging fry remain with the box until they become free swimming at which time they can escape through the openings in the box. However, these boxes exhibit a common deficiency in that the eggs rest on the box bottom and silt tends to deposit around the eggs which lessens the exposure of the eggs to the water as a consequence of which some eggs smother and fungus attack also occurs, although in general the fry survival rate exceeds that obtained under natural conditions.